Method and device for aligning sheets in a transport module

ABSTRACT

A transport module for deskewing and accumulating sheets of insert materials before the sheets are inserted into an envelope for mailing. Retractable gates are used to stop the sheets as they are separately moved into the transport module by a plurality of endless belts. Idlers are used to apply normal forces on the belts at various locations to provide traction between the sheet and the belts for moving the sheet forward. If a sheet is skewed when it enters the transport module, one corner on the leading edge of the sheet encounters one of the side gates and the advancing sheet can align itself by an angular motion using the contact point as center of rotation. As such, the leading edge is registered against the retractable gates at both sides of the leading edge. The transport module can also be used as a conveyor without the accumulation function.

TECHNICAL FIELD

The present invention relates generally to a mail inserter and, more particularly, a device that can selectively transport or deskew and accumulate elements of a mailpiece.

BACKGROUND OF THE INVENTION

A typical mailing machine has a mail inserter section 3 where a pack of insert material 20 is inserted into an envelope 30, as shown in FIG. 1. The mailing machine also has an accumulation section 1 where a plurality of insert documents 10 are fed and accumulated into a stack 12. The accumulation section typically has one or more enclosure feeders to separately release individual sheets of insert documents into a collection deck to be accumulated. The accumulated documents may be folded in a folder/feeder 2. The mailing machine may also have a printing section for printing the insert documents or the envelopes.

Before the accumulated documents are folded into a pack or moved into a receiving envelope, the individual sheets must be aligned to one another. However, one or more of the sheets may be skewed when they are released. This means that the leading edge of one sheet may not be registered to the leading edge of the others. In prior art accumulators, the sheets are aligned against one or more side guides parallel to the moving direction of the sheets. The sheets are typically urged to register against the side guides by a system of light drive forces. These accumulators are inadequate when transporting media of variable widths and thickness. The fixed side guides cannot accommodate variable widths and the light drive forces may not be sufficient to accelerate thick materials without slippage.

It is thus desirable and advantageous to provide a method and system for aligning the insert materials in an accumulator where the leading edge of an individual sheet can be aligned independently of side registration devices.

SUMMARY OF THE INVENTION

The present invention provides a transport module in a mailing machine to deskew and accumulate sheets of insert materials before the sheets are inserted into an envelope for mailing. The transport module uses a plurality of retractable gates to stop the insert materials as they are separately moved into the transport module by a plurality of endless belts. A plurality of idlers are used to apply normal forces on the belts at various locations to provide traction between the sheet and the belts for moving the sheet forward. If a released sheet is skewed when it enters the transport module, one of the corners on the leading edge of the sheet encounters one of the side gates in the transport module. The advancing sheet may be able to align itself by an angular motion using the contact point as the center of rotation. As such, the leading edge can be registered against the retractable gates at both sides of the leading edge. However, this is possible only if the traction between the sheet and belts is greater than the moment associated with the friction between the sheet and the existing stack as the skewed sheet experiences the angular motion. According to the present invention, the normal forces applied to the advancing sheet are dependent upon the location of the idlers. In particular, the normal forces are distributed such that the normal forces are stronger at locations nearer to the retractable gates than the normal forces at locations farther from the retractable gates. Furthermore, a number of pivotable hold-down mechanisms are disposed near the retractable gates to prevent the leading edge from buckling up.

Additionally, the transporting module can be programmed to selectively skip the accumulation mode so that insert materials can be moved into the envelope without being stacked up before insertion. Insert materials such as booklets, folded sheets, cards, mailpieces or other envelopes can be conveyed through the transport module to the waiting envelope. These insert materials can be conveyed through the transport module with or without the sheets to be accumulated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a typical mailing machine.

FIG. 2 a is a schematic representation of a mailing machine, according to the present invention.

FIG. 2 b is a schematic representation of a different mailing machine, according to the present invention.

FIG. 3 a is a schematic representation showing a sheet of insert material being released into an accumulation section of a mailing machine.

FIG. 3 b is a schematic representation showing the sheet of insert material aligning itself against a plurality of registration gates.

FIG. 3 c is a schematic representation showing a sheet of insert material being released into an accumulation section of a mailing machine, wherein the sheet is skewed.

FIG. 3 d is a schematic representation showing the skewed sheet experiencing an angular motion after one of the leading-edge corners is stopped by one of the side gates.

FIG. 4 is a schematic representation showing a plurality of locations where normal forces are provided on a plurality of driving belts.

FIG. 5 a is a schematic representation showing the normal forces applied on different locations of a driving belt.

FIG. 5 b is a schematic representation showing a plurality of idlers being used for providing the normal forces.

FIG. 6 is a perspective view of the transport module of the present invention.

FIG. 7 shows the details of a front portion of the transport module.

FIG. 8 is a side view of the transport module showing a drive belt and a plurality of idlers for applying normal forces on the belt.

FIG. 9 is a plan view of the transport module of the present invention.

FIG. 10 shows the details of a back portion of the transport module.

FIG. 11 a shows the transport module being used as a conveyor.

FIG. 11 b shows the dual-function of the transport module, according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a transport module 100 for use in a mailing machine, which allows a sheet of insert material to align itself when it is released and moved into the transport module. The transport module, according to the present invention, can be programmed to function like an accumulator. It can also be programmed to function like a simple conveyor. These two functions can exist alternately in a continuous operation. The transport module 100 is capable of transporting insert materials of various thickness, lengths and widths. The transport module 100 can be used to provide insert materials to a mail inserter section 300, with or without a folder/feeder 200, as shown in FIGS. 2 a and 2 b. A feeder 90 (see the releasing mechanism 180 in FIG. 10) is used to release the mailing materials on to the transport module 100.

When the transport module 100 is used as an accumulator, the sheets released into the transport module are registered against a plurality of registration gates so that they form a stack in the transport module. These registration gates are retractable such that when the accumulation of a stack is completed, the gates are retracted to allow the stack of insert material to move forward to the next section of the mailing machine.

The movement of a released sheet in the transport module 100 is shown in FIGS. 3 a to 3 d. As shown in FIG. 3 a, a sheet of insert material 10 is released on top of another sheet 10′ already in the transport module 100. The released sheet 10 moves along a movement direction 104 until it is registered against the registration gates 110, as shown in FIG. 3 b. FIG. 3 c shows a sheet of insert material 10 which is skewed when it is moved into the transport module 100. The skewed sheet moves along the direction 104 until one of the corners of its leading edge is blocked by one of the registration gates 110. After the skewed sheet 10 is stopped by the registration gate at a contact point, as shown in FIG. 3 d, it experiences an angular motion as indicated by an arrow 106, using the contact point as the center of rotation. This angular motion continues until the both sides of the leading edge are registered against the registration gates, as shown in FIG. 3 b.

As shown in FIG. 4, a plurality of driving belts 1201, 1202, 1203 are used to move insert materials, one sheet at a time, into the transport module along the movement direction 104. In order to provide sufficient traction between the belts and the sheet 10 (not shown) so the sheet can be moved into the stacking position, normal forces are applied at a plurality of locations (xn, ym). Here the coordinates x, y are relative to a potential contact point (0,0) at the rightmost registration gate (see FIG. 3 d). In this exemplary embodiment, n=3 and m=5. However, the number of driving belts and the number of locations where the normal forces applied on each driving belt can be different from 3 and 5, depending on the size of the insert materials.

After one corner of a skewed sheet is stopped by a registration gate at a contact point as shown in FIG. 3 d, the traction between the belts and the sheet causes the sheet 10 to rotate along the direction 106. This angular motion, however, is countered by the frictional force between the sheet 10 and the sheet 10′ below. The action by the traction (deskew moment) and the counter-action by the frictional force (anti-deskew moment) are related to the normal forces Fnm applied at point (xn, ym). In order to allow the sheet to align itself against the registration gates, the deskew moment must be greater than the anti-deskew moment.

Assuming that the frictional coefficient between the belts and the sheet is ubp and the frictional coefficient between two sheets of insert material is ubp, self-alignment of the insert materials in the accumulator is possible if ${{upb}{\sum\limits_{m}{\sum\limits_{n}{F_{n\quad m}x_{n}}}}} > {{upp}{\sum\limits_{m}{\sum\limits_{n}{F_{n\quad m}D_{\quad{n\quad m}}}}}}$ where D_(nm) is the distance between point (0,0) and point (xn, ym). As shown in the above equation, the term F_(nm) D_(nm) becomes more dominant when the distance D_(nm) becomes greater. In order to reduce the dominant factors attributable to the normal forces at such locations as (X_(n), y₄) and (x_(n), y₅), as shown in FIG. 5 a, it is desirable to have F_(n5)<<F_(n1), for example.

According to the present invention, normal forces F_(nm) are provided by a plurality of idlers 131, 132, 133, 134, 135 at points (xn, y1), (xn, y2), (xn, y3), (xn, y4), (xn, y5), respectively, as shown in FIGS. 5 b-9. At points (xn, y3), (xn, y4), (xn, y5), the idlers 133, 134, 135 are allowed to float, or move up and down freely about their pivot (see FIG. 8). Thus, the normal forces applied at these locations are mainly determined by the weight of the idlers and the idler pivot arms. In order to increase the normal forces at points (xn, y1) and (xn, y2), the idlers 131, 132 are loaded against the driving belts 120 n by springs 141 and 142, as shown in FIG. 7.

The retractable gates 110 that are used for leading edge registration are shown in FIG. 7. In a mailing machine wherein the sheets are released and moved into the transport module at high speed, it is desirable to protect the leading edge of the sheets when it is blocked by the registration gates. According to the present invention, at least one hold-down ski 150 is used to hold-down the leading edge of the stack. As shown in FIG. 7, the hold-down ski 150 is supported by a freely pivotable arm 154 in order to reduce the friction between the ski and the sheet below. The forward edge 152 of the hold-down ski 150 is adjacent to the retractable gates. A plurality of ski fingers 156 are provided on the forward edge 152 between the retractable gates. The forward edge 152 and the ski fingers 156 prevent the leading edge of the accumulated sheets to buck up and damage.

As shown in FIG. 8, the belts 120 n are driven by rollers 160 and 162. FIG. 9 is a plan view of the accumulator without the driving belts. FIG. 10 depicts the details of the back section of the transport module, showing how the trailing edge of a sheet 10 is positioned so that the leading edge of a subsequent sheet 10″ is prevented from hitting the trailing edge of the previous sheet 10. As shown in FIG. 10, the trailing edge 17 of the previous sheet 10 is biased downward by the arrangement of the driving roller 160 and a supporting idler 170. By offsetting the contact point 172 of the support idler 170 from the center line 164 of the driving roller 164, the nip 176 formed by the driving roller 164 and the support idler 170 bends the trailing edge 17 of the sheet 10 downward. Along with the precise start stop aspect of the releasing mechanism 180 and the driving belts 120 n, the subsequent sheet 10″ is always positioned above the trailing edge 17 of the previous sheet 10″ when the subsequent sheet 10″ is released toward the nip 176.

When the transport module 100 is used as a conveyor, it typically allows insert materials to be conveyed from the upstream direction to the inserting station where the insert materials are inserted into a waiting envelope. As shown in FIG. 11 a, the feeder 90 located upstream from the transport module 100 is used to release the insert materials. The insert materials, as shown in FIG. 11 a, may include a card 6, a booklet 7, a folded sheet 8, and a regular sheet 10. Some of these insert materials are moved by the transport module 100 into the envelope 30 while some will be moved into the next envelope (not shown). In this operation mode, the registration gates 110 (see FIG. 7) are always in a retracted position. Other materials such as envelopes can also be moved to the inserting section 300 by the transport module 100. These materials can have different thickness, length and width. For example, the transport module can transport sheets about 0.004″ (about 0.01 cm) thick, having a width from 5″ to 10″ (about 12.7 to 25.4 cm) and a length from 5″ to 14″ (about 12.7 to 35.6 cm); booklets up to 0.16″ (about 0.4 cm), tri-folds having a length from about 2.8″ to 11.8″ (7.2 cm to 30 cm), etc. So long as the width of the mailing items to be transported falls within a predetermined range, the transport module can accommodate those mailing items without the need of adjustment.

FIG. 11 b illustrates the dual-nature of the transport module, according to the present invention. As shown, the upstream feeder 90 delivers a plurality of sheets 10 to be accumulated, a folded sheet 8 and a booklet 7 to the transport module 100. The transport module 100 is programmed to accumulate all the sheets 10 into a stack 12 before inserting the stack 12 into the envelope 30. However, the folded sheet 8 and the booklet 7 are separately and sequentially moved by the transport module 100 into the envelope 30 after the stack 12 has been inserted.

It is understood that the range of thickness, widths and lengths of the insert material is dependent upon the dimensions and design of the transport module and the dimensions of the envelope 30. One skilled in the art can reduce or increase the number of belts, the number of idlers to suit the need. Thus, although the invention has been described with respect to one or more embodiments thereof, it will be understood by those skilled in the art that the foregoing and various other changes, omissions and deviations in the form and detail thereof may be made without departing from the scope of this invention. 

1. A method to transport mailing materials along a moving direction by a moving mechanism in a transport module for use in a mailing machine, the mailing materials including sheets to be accumulated, wherein each of the sheets is moved into the transport module along the moving direction, and the transport module comprises a registration barrier substantially perpendicular to the moving direction so as to allow a leading edge of each of the sheets to register against the registration barrier, the leading edge of each sheet has a first side and an opposing second side, the sheets including a current sheet and a previous sheet, the current sheet having a frictional force against the previous sheet, the transport module at least operable in a first mode to accumulate the sheets, said method comprising the steps of: providing a moving surface on the moving mechanism adjacent to the current sheet; and distributing a plurality of normal forces at a plurality of locations for urging the moving surface of the moving mechanism against the current sheet so as to produce a traction between the moving surface and the current sheet, such that, when the transport module is operated in the first mode, the traction is able to overcome the frictional force so as to continue moving the second side of the leading edge of the current sheet until it contacts the registration barrier, if the first side of the leading edge of the current sheet contacts the registration barrier before the second side.
 2. The method of claim 1, further comprising the step of: retracting the registration barrier after the sheets have been accumulated so as to allow the accumulated sheets to move further along the moving direction.
 3. The method of claim 1, wherein the registration barrier is retractable and the mailing materials include mail items, and wherein the transport module is operable in a second mode, said method comprising the step of: retracting the registration barrier when the transport module is operated in the second mode so as to allow the mail items to move further along the moving direction separately and sequentially.
 4. The method of claim 1, wherein the transport module is operable between the first mode and a second mode and the registration barrier is operable is a first position and a second position, and wherein the mailing materials also include mail items, said method further comprising the steps of: maintaining the registration barrier in the first position when the transport module is operated in the first mode, such that if the first side of the leading edge of the current sheet contacts the registration barrier before the second side, the traction is able to overcome the frictional force so as to continue moving the second side of the leading edge of the current sheet until it contacts the registration barrier; and retracting the registration barrier to the second position after the sheets have been accumulated so as to allow the accumulated sheets to move further along the moving direction, and when the transport module is operated in the second mode so as to allow the mail items to move further along the moving direction separately and sequentially.
 5. The method of claim 1, wherein the moving surface comprises a plurality of moving belts and the transport module comprises a plurality of weighting objects distributed at the plurality of locations for providing the normal forces to urge the moving belts against the current sheet.
 6. A transport module for use in a mailing machine to move and a plurality of mailing materials in a moving direction toward a downstream direction, the transport module at least operable in a first mode, wherein the mailing materials comprise sheets to be accumulated, the sheets having a current sheet and a previous sheet, the current sheet having a frictional force against the previous sheet, said transport module comprising: a moving mechanism for moving each of the sheets along the moving direction, each sheet having a leading edge, the leading edge having a first side and an opposing second side, the moving mechanism having a moving surface adjacent to the current sheet; a registration barrier operable in a first position and in a second position, the barrier substantially perpendicular to the moving direction so as to allow the leading edge of each of the sheets to register against the registration barrier when the transport module is operated in the first mode and the barrier is operated in the first position, and a plurality of weighting objects distributed at a plurality of locations for urging the moving surface of the moving mechanism against the current sheet so as to produce a traction between the moving surface and the current sheet, such that if the first side of the leading edge of the current sheet contacts the registration barrier before the second side, the traction is able to overcome the frictional force so as to continue moving the second side of the leading edge until it contacts the registration barrier.
 7. The transport module of claim 6, wherein the registration barrier is retractable to the second position so as to allow the sheets to move toward the downstream direction after the sheets have been accumulated.
 8. The transport module of claim 6, wherein the mailing materials include mail items, and the transport module is also operable in a second mode so that, when the transport module is operated in the second mode, the registration barrier is retractable to the second position so as to allow the mail items to be moved toward the downstream direction separately and sequentially.
 9. The transport module of claim 8, wherein the mailing items include one or more cards.
 10. The transport module of claim 8, wherein the mailing items include one or more folded sheets.
 11. The transport module of claim 12, wherein the mailing items include one or more booklets.
 12. The transport module of claim 7, wherein the mailing materials include mail items, and the transport module is operable between the first mode and a second mode such that, when the transport module is operated in the first mode, the registration barrier is operated in the first position so as to allow the leading edge of each of the sheets to register against the registration barrier, and if the first side of the leading edge of the current sheet contacts the registration barrier before the second side, the traction is able to overcome the frictional force so as to continue moving the second side of the leading edge until it contacts the registration barrier; and the registration barrier is retracted to the second position after the sheets have accumulated so as to allow the accumulated sheets to move further toward the downstream direction; and when the transport module is operated in the second mode, the registration barrier is retracted to the second position so as to allow the mail items to move separately and sequentially along the moving direction toward the downstream direction. 